In medicine, in particular in ophthalmology, laser-based treatment systems are used to perform minimally invasive procedures on the human body. In this context, different laser wavelengths are used for different treatments on the eye. For example, when diode lasers are used, output powers in the range of approximately 400 mW in the long-wave spectral region of 690 nm are used for photodynamic treatments.
In ophthalmology, it is known to use high-power diode lasers, inter alia, for “transpupillary thermotherapy” (TTT), a wavelength of 810 nm being applied at an output power of approximately 650 mW.
Moreover, ophthalmological laser devices employ a diode laser that is operated in the red wavelength region at a non-damaging output power of less than 1 mW, as to produce what is commonly known as a pilot or alignment beam, in order to adjust the focus of the radiation to the specific application prior to applying the therapeutic useful radiation.
Various technical approaches from the non-ophthalmological sector are described in World Patent Applications WO 91/12641 and WO 95/14251, which provide for coupling two or more laser diodes into individual optical fibers.
One widely used ophthalmological laser therapy is what is commonly known as laser coagulation of the retina. It is used, for example, in the treatment of “diabetic retinopathy.” Particularly of interest for modified therapies in this context are the green, yellow and red spectral regions which are covered by multiwavelength systems on the basis of gas lasers and purely diode-pumped and frequency-multiplied solid-state laser systems, as described in the World Patent Application WO 02/21646 A1 and the European Patent EP 1 184 947.
However, under the related art, multiwavelength systems disadvantageously necessitate a large volume, a large mass, a high complexity and a substantial energy demand and, at the same time, they give off considerable heat, resulting in increased costs for manufacturing, operating and maintaining such systems.